32 Can Science Explain Life? 



facts, for it has been found that the amounts of 

 hydrogen chloride gas which are taken up by pro- 

 teins are much smaller than the amounts which 

 they should take up if they were ordinary poly- 

 peptide structures. 



On the other hand, the amount of acid which a 

 protein is capable of neutralizing is always much 

 greater than the amount which could be taken up 

 by the terminal — NH 2 groups, which never con- 

 tain more than about ten percent of the total 

 protein nitrogen. Similarly the amount of base 

 which a protein is capable of neutralizing is 

 always much greater than the amount which 

 could be taken up by the terminal — CO — OH 

 groups, assuming these to be about equal in num- 

 ber to the — NH 2 groups. It must therefore be 

 concluded that the ability of proteins to neutralize 

 acids and bases is due not only to the terminal 

 amino and carboxyl groups, but also, in a large 

 measure, to the peptide groups — CO — NH — 

 along the sides of the spirazines. 



In the spirazine structure shown in Figs, la and 

 lb, the alternate peptide groups are connected to 

 one another by means of the fourth and fifth 

 valencies of the nitrogen atoms, and also by 

 means of the oxygen atoms, but these connections 

 are probably not very permanent and may change 

 over into the enol-form shown in Figs, lc and Id, 



